Production of textiles



- Patented June 6, 1939 PATENT OFFICE PRODUCTION OF TEXTILES Ernst Freund, Vienna, Austria, assignor to E. L du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No. Drawing. Application March 14, 1936, Serial 8 Claims.

This invention relates to the production of g tures which, by virtue of their treatment in accordance with the invention, have the property of shrinking when moistened with water and then dried. If for example such shrinking threads be woven alternately with ordinary threads (not treated in accordance with the invention), for instance as weft, and if the fabric thus produced be then moistened with water and finally dried, crepe-like effects are obtained. It is also possible, with partial or exclusive use of shrinking threads (ribbons or the like) to produce any other superficial textile structures.

The process according to the present invention consists in treating structures, and more particularly threads, ribbons, and the like, made from regenerated cellulose with saline shrinking agents or solutions thereof, while preventing shrinking, after which, still with prevention of shrinking, the structures are freed from the shrinking agents by washing, and finally dried.

The saline shrinking agents contemplated for use in accordance with the present invention are comprised in the following classes:

(a) Those which, in the absence of special measures for preventing shrinkage, exert a shrinking action upon regenerated cellulose even in aqueous solution, at suitable temperature;

(b) Those which only when drying on or in the fibre so alter the cellulose that, after washing out of the shrinking agent and subsequent drying of the fibre, shrinkage occurs provided such shrinking-be not inhibited by special mechanical measures.

Group a comprises primarily the water-soluble lithium-salts, the thiocyanates of the alkali and alkaline earth metals, alkali acetates, and other salts of considerable degree of hydration (cf. R. O. Herzog, "Zeitschrift fiir .Physiologische Chemie, No. 111, page 287).

The specified salts are employed with advantage in concentrated aqueous solution. I have found that the hydration, and with it the shrinking power, of solutions of hydrated salts is dependent in a peculiar manner on the temperature at which the treatment is carried out and on the valency of the cation concerned, this dependence, being such that at lower temperature the solutions of hydrated salts with univalent cation exert a more powerful shrinking action, while at higher temperature the solutions of hydrated salts with biand multivalent cation exert In Austria March 15, 1935 a more powerful shrinking action. An exception to this rule is provided by the lithium salts which behave as if lithium were a bivalent cation.

There results the possibility of varying the shrinking action of the salt solutions at will, and 6 therefore also the extent of the shrinkage effected in shrinking threads or structures produced in accordance with the present invention, to conform to a desired standard. A limit is set to the extent to which the shrinking action of the salt solutions is increased by the requirement that the structures made from regenerated cellulose be not dissolved or impaired as to their mechanical properties.

The shrinking action of the salt solution is 15 also dependent on the concentration of these solutions.

It is noteworthy that solutions of mixtures of hydrated salts often have a more powerful shrinking action than the individual constituents of the 20 mixtures when used singly at the same degree of concentration.

I have also found that an addition of starch or of cellulose decomposition products which are soluble in water increases the shrinking action 25 of the salt solutions.

The above-mentioned Group b of saline shrinking agents comprises almost all salts of which a concentrated aqueous solution shows no direct shrinking action. These salts have on the contrary the property, when applied to the fibre, of so altering the fibre that it only shows a tendency to shrink after the applied shrinking agent has been washed out and the fibre dried. This property is possessed to a particularly marked ex- 35 tent by the inorganic calcium salts, such as for example calcium chloride, calcium bromide, and the like, as also by the organic calcium salts such" as for example calcium acetate, insofar as they do not exert a direct shrinking action in aqueous solution.

The treatment in accordance with the invention with the saline compounds included in Group b can be carried out for instance by first tensioning "Rayon in a suitable manner in a dry state or in any desired swelled state, for example by winding the same under tension on to a bobbin. The thus tensioned material is then steeped in the concentrated salt solution, the surplus solution removed by any suitable means, for example by centrifuging, and the thus treated material then dried at elevated temperature until it feels dry. The salts are then washed out of the material and the material dried, both these steps preventing the shrinkage thereof.

being carried out while the material is still on the bobbin.

The above described method of treatment can also be adopted with solutions of the salts comprised in Group a, in which case the resulting effect is increased.

A modified form of the process, applicable only when salts of Group b are used, consists in steeping the material, for example "Rayo1:, in the non-tensioned state with solutions of these salts, since these solutions do not exert any direct shrinking action. The subsequent drying of the steeped fibre can also be carried out without the latter being in tension, since the salt particles lodged therein prevent shrinkage. The washing out of the salts and the subsequent drying must, however, be carried out with the material under tension.

Examples (1) Viscose silk is wound dry or wet on a bobbin, or taken as it comes from the spinning process on bobbins, and treated, in the de-sulphurized or in the non-de-sulphurized condition, with concentrated potassium thiocyanate solution at a temperature of 10 C., then thoroughly washed and dried. If the thus treated silk be moistened with water and dried, without tensioning, it undergoes a shrinkage of about 8%.

(2) As Example 1 except that as the treatment bath there is used a concentrated calcium thiocyanate solution at a temperature of 25 0., instead of the potassium thiocyanate solution at 10 C.

(3) Viscose silk is wound moist on a bobbin, treated with concentrated calcium chloride solution, dried on the bobbin atelevated temperature, washed out, and once more dried. The silk is then skeined. If the treated silk be then wetted and dried, without being tensioned, it shrinks to the extent of 6%.

(4) As Example 3 except that a potassium thiocyanate solution of 40% strength is used instead of the calcium chloride solution.

I claim:

1. The process of imparting a high potential shrinkage to a regenerated cellulose thread which comprises treating said thread with an aqueous solution of a solid thread shrinking agent while preventing the shrinkage of said threads, and drying said thread while preventing the shrinkage thereof.

2. The process of imparting a high potential shrinkage to a regenerated cellulose thread which comprises treating. said thread with a concentrated aqueous solution of asolid saline thread shrinking agent while preventing the shrinkage of said threads, and drying said thread while 3. The process of imparting a high potential shrinkage to a regenerated cellulose thread which 1 comprises treating said thread with a concentrated aqueous solution of a solid hydrated salt thread shrinking agent while preventing the taken from the group consisting of hydrated alkali 'metal and alkali earth metal salts While preventing the shrinkage of said threads, and drying said thread while preventing the shrinkage thereof.

5. In the process of making a fabric, the steps comprising weaving together regenerated cellulose thread treated with an aqueous solution of a solid thread shrinking agent to impart thereto a high potential shrinkage, said treatment being applied while holding the thread to prevent the shrinkage thereof, and regenerated cellulose thread having a low potential shrinkage, moistening said fabric, and drying the same.

6. In the process of making a fabric, the steps comprising weaving together regenerated cellulose thread treated with a concentrated aqueous solution of a solid saline thread shrinking agent to impart thereto a high potential shrinkage, said treatment being applied while holding the thread to prevent the shrinkage thereof, and regenerated cellulose thread having a low potential shrinkage, moistening said fabric, and drying the same.

'7. In the process of making a fabric, the steps comprising weaving together regenerated cellulose thread treated with a concentrated aqueous solution of a solid hydrated salt thread shrinking agent to impart thereto a high potential shrinkage, said treatment being applied while holding the thread to prevent the shrinkage thereof, and regenerated cellulose thread having a low potential shrinkage, moistening said fabric, and drying the same.

8. In the process of making a fabric, the steps comprising weaving together regenerated cellulose thread treated with an aqueous solution of a solid saline thread treating agent taken from the group consisting of hydrated alkali metal and alkaline earth metal salts to impart thereto a high ERNST FREUN D. 

